86 research outputs found
A Review of Cooperative Actuator and Sensor Systems Based on Dielectric Elastomer Transducers
This paper presents an overview of cooperative actuator and sensor systems based on
dielectric elastomer (DE) transducers. A DE consists of a flexible capacitor made of a thin layer
of soft dielectric material (e.g., acrylic, silicone) surrounded with a compliant electrode, which is
able to work as an actuator or as a sensor. Features such as large deformation, high compliance,
flexibility, energy efficiency, lightweight, self-sensing, and low cost make DE technology particularly
attractive for the realization of mechatronic systems that are capable of performance not achievable
with alternative technologies. If several DEs are arranged in an array-like configuration, new concepts
of cooperative actuator/sensor systems can be enabled, in which novel applications and features
are made possible by the synergistic operations among nearby elements. The goal of this paper is
to review recent advances in the area of cooperative DE systems technology. After summarizing
the basic operating principle of DE transducers, several applications of cooperative DE actuators
and sensors from the recent literature are discussed, ranging from haptic interfaces and bio-inspired
robots to micro-scale devices and tactile sensors. Finally, challenges and perspectives for the future
development of cooperative DE systems are discussed
Enabling wearable soft tactile displays with dielectric elastomer actuators
PhDTouch is one of the less exploited sensory channels in human machine
interactions. While the introduction of the tactile feedback would improve the
user experience in several fields, such as training for medical operators,
teleoperation, computer aided design and 3D model exploration, no interfaces
able to mimic accurately and realistically the tactile feeling produced by the
contact with a real soft object are currently available. Devices able to simulate
the contact with soft bodies, such as the human organs, might improve the
experience.
The existing commercially available tactile displays consist of complex
mechanisms that limit their portability. Moreover, no devices are able to provide
tactile stimuli via a soft interface that can also modulate the contact area with the
finger pad, which is required to realistically mimic the contact with soft bodies,
as needed for example in systems aimed at simulating interactions with virtual
biological tissues or in robot-assisted minimally invasive surgery.
The aim of this thesis is to develop such a wearable tactile display based on the
dielectric elastomer actuators (DEAs). DEAs are a class of materials that respond
to an electric field producing a deformation.
In particular, in this thesis, the tactile element consists of a so-called
hydrostatically coupled dielectric elastomer actuator (HC-DEAs). HC-DEAs rely
on an incompressible fluid that hydrostatically couples a DEA-based active part
to a passive part interfaced to the user.
The display was also tested within a closed-loop configuration consisting of a
hand tracking system and a custom made virtual environment. This proof of
concept system allowed for a validation of the abilities of the display.
Mechanical and psychophysical tests were performed in order to assess the
ability of the system to provide tactile stimuli that can be distinguished by the
users.
Also, the miniaturisation of the HC-DEA was investigated for applications in
refreshable Braille displays or arrays of tactile elements for tactile maps
A Soft touch: wearable dielectric elastomer actuated multi-finger soft tactile displays
PhDThe haptic modality in human-computer interfaces is significantly underutilised when compared to that of vision and sound. A potential reason for this is the difficulty in turning computer-generated signals into realistic sensations of touch. Moreover, wearable solutions that can be mounted onto multiple fingertips whilst still allowing for the free dexterous movements of the user’s hand, brings an even higher level of complexity. In order to be wearable, such devices should not only be compact, lightweight and energy efficient; but also, be able to render compelling tactile sensations. Current solutions are unable to meet these criteria, typically due to the actuation mechanisms employed. Aimed at addressing these needs, this work presents research into non-vibratory multi-finger wearable tactile displays, through the use of an improved configuration of a dielectric elastomer actuator. The described displays render forces through a soft bubble-like interface worn on the fingertip. Due to the improved design, forces of up to 1N can be generated in a form factor of 20 x 12 x 23 mm, with a weight of only 6g, demonstrating a significant performance increase in force output and wearability over existing tactile rendering systems. Furthermore, it is shown how these compact wearable devices can be used in conjunction with low-cost commercial optical hand tracking sensors, to cater for simple although accurate tactile interactions within virtual environments, using affordable instrumentation. The whole system makes it possible for users to interact with virtually generated soft body objects with programmable tactile properties. Through a 15-participant study, the system has been validated for three distinct types of touch interaction, including palpation and pinching of virtual deformable objects. Through this investigation, it is believed that this approach could have a significant impact within virtual and augmented reality interaction for purposes of medical simulation, professional training and improved tactile feedback in telerobotic control systems.Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Centre EP/G03723X/
Electroactive polymers for sensing.
Electromechanical coupling in electroactive polymers (EAPs) has been widely applied for actuation and is also being increasingly investigated for sensing chemical and mechanical stimuli. EAPs are a unique class of materials, with low-moduli high-strain capabilities and the ability to conform to surfaces of different shapes. These features make them attractive for applications such as wearable sensors and interfacing with soft tissues. Here, we review the major types of EAPs and their sensing mechanisms. These are divided into two classes depending on the main type of charge carrier: ionic EAPs (such as conducting polymers and ionic polymer-metal composites) and electronic EAPs (such as dielectric elastomers, liquid-crystal polymers and piezoelectric polymers). This review is intended to serve as an introduction to the mechanisms of these materials and as a first step in material selection for both researchers and designers of flexible/bendable devices, biocompatible sensors or even robotic tactile sensing units.This is the final version of the article. It first appeared from The Royal Society Publishing via https://doi.org/10.1098/rsfs.2016.002
Dielectric Elastomer Cooperative Microactuator Systems : DECMAS
This paper presents results of the first phase of “Dielectric Elastomer Cooperative Microactuator Systems” (DECMAS), a project within the German Research Foundation Priority Program 2206, “Cooperative Multistable Multistage Microactuator Systems” (KOMMMA). The goal is
the development of a soft cooperative microactuator system combining high flexibility with largestroke/high-frequency actuation and self-sensing capabilities. The softness is due to a completely
polymer-based approach using dielectric elastomer membrane structures and a specific silicone bias
system designed to achieve large strokes. The approach thus avoids fluidic or pneumatic components, enabling, e.g., future smart textile applications with cooperative sensing, haptics, and even
acoustic features. The paper introduces design concepts and a first soft, single-actuator demonstrator
along with experimental characterization, before expanding it to a 3 × 1 system. This system is
used to experimentally study coupling effects, supported by finite element and lumped parameter
simulations, which represent the basis for future cooperative control methods. Finally, the paper
also introduces a new methodology to fabricate metal-based electrodes of sub-micrometer thickness
with high membrane-straining capability and extremely low resistance. These electrodes will enable
further miniaturization towards future microscale applications
Finite element modeling and validation of a soft array of spatially coupled dielectric elastomer transducers
Dielectric elastomer (DE) transducers are suitable candidates for the development of compliant mechatronic devices, such as wearable smart skins and soft robots. If many independently-controllable DEs are closely arranged in an array-like configuration, sharing a common elastomer membrane, novel types of cooperative and soft actuator/sensor systems can be obtained. The common elastic substrate, however, introduces strong electro-mechanical coupling effects among neighboring DEs, which highly influence the overall membrane system actuation and sensing characteristics. To effectively design soft cooperative systems based on DEs, these effects need to be systematically understood and modeled first. As a first step towards the development of soft cooperative DE systems, in this paper we present a finite element simulation approach for a 1-by-3 silicone array of DE units. After defining the system constitutive equations and the numerical assumptions, an extensive experimental campaign is conducted to calibrate and validate the model. The simulation results accurately predict the changes in force (actuation behavior) and capacitance (sensing behavior) of the different elements of the array, when their neighbors are subjected to different electro-mechanical loads. Quantitatively, the model reproduces the force and capacitance responses with an average fit higher than 93% and 92%, respectively. Finally, the validated model is used to perform parameter studies, aimed at highlighting how the array performance depends on a relevant set of design parameters, i.e. DE-DE spacing, DE-outer structure spacing, membrane pre-stretch, array scale, and electrode shape. The obtained results will provide important guidelines for the future design of cooperative actuator/sensor systems based on DE transducers
Study on conductive hydrogels in flexible and wearable triboelectric devices towards energy-harvesting and sensing applications (エネルギーハーベスティングおよびセンシングに向けたフレキシブルでウェアラブルな摩擦発電デバイスにおける導電性ハイドロゲルに関する研究)
信州大学(Shinshu university)博士(工学)この博士論文は、次の学術雑誌論文を一部に使用しています。 / ACS Applied Materials Interfaces 14(7) :9126-9137(2022); doi:10.1021/acsami.1c23176 / Advanced Fiber Materials 4(6) :1486-1499(2022); doi:10.1007/s42765-022-00181-4 / Chemical Engineering Journal 457 :141276(2023); doi:10.1016/j.cej.2023.141276ThesisDONG, LI. Study on conductive hydrogels in flexible and wearable triboelectric devices towards energy-harvesting and sensing applications (エネルギーハーベスティングおよびセンシングに向けたフレキシブルでウェアラブルな摩擦発電デバイスにおける導電性ハイドロゲルに関する研究). 信州大学, 2023, 博士論文. 博士(工学), 甲第802号, 令和05年03月20日授与.doctoral thesi
HapBead: on-skin microfluidic haptic interface using tunable bead
On-skin haptic interfaces using soft elastomers which are thin and flexible have significantly improved in recent years. Many are focused on vibrotactile feedback that requires complicated parameter tuning. Another approach is based on mechanical forces created via piezoelectric devices and other methods for non-vibratory haptic sensations like stretching, twisting. These are often bulky with electronic components and associated drivers are complicated with limited control of timing and precision. This paper proposes HapBead, a new on-skin haptic interface that is capable of rendering vibration like tactile feedback using microfluidics. HapBead leverages a microfluidic channel to precisely and agilely oscillate a small bead via liquid flow, which then generates various motion patterns in channel that creates highly tunable haptic sensations on skin. We developed a proof-of-concept design to implement thin, flexible and easily affordable HapBead platform, and verified its haptic rendering capabilities via attaching it to users’ fingertips. A study was carried out and confirmed that participants could accurately tell six different haptic patterns rendered by HapBead. HapBead enables new wearable display applications with multiple integrated functionalities such as on-skin haptic doodles, mixed reality haptics and visual-haptic displays
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